Question

Design a timing circuit that provides an output signal that stays on for exactly twelve clock cycles. A start signal sends the output to the 1 state, and after twelve clock cycles the signal returns to the 0 state.

Answer 1

Explanation:

( Check attachment for the design )

When capacitor is charging

$V_{c} = V_{cc} ( 1- e^{\frac{t}{Rc} })$

At

t = $t_{0}$

$V_{C}$ becomes $\frac{2V_{cc} }{3} = V_{cc} ( 1- e^{\frac{-t0}{Rc} } )$

$\frac{e^{t0} }{Rc} = 3$

$T_{0} = 1.1 Rc$

$T_{0} = 12 = 1.1 Rc$

Rc = 10.909

So , Assume R = 10 MΩ

                     C = 1.0909 μ F